Understanding Rosacea · Chapter 2
What Causes Rosacea? Understanding the Aetiology
Rosacea does not have a single cause. It develops through a mix of genetic susceptibility, an overactive immune system, sensitive nerves and blood vessels, skin microbes and a weakened skin barrier.
What causes rosacea?
Rosacea is driven by a chronically overactive innate immune system, oversensitive nerves and blood vessels, Demodex mites and their bacteria, genetic susceptibility and a compromised skin barrier. Triggers such as heat or alcohol switch these pathways on in people who are already predisposed; they do not cause rosacea on their own.
What is cathelicidin and why does it matter in rosacea?
Cathelicidin is a natural antimicrobial peptide. In rosacea skin it is produced in higher amounts and processed into abnormal fragments by an enzyme called kallikrein-5, which drive redness, inflammation and new blood vessel growth.
Do Demodex mites cause rosacea?
Demodex mites live on the skin of most adults, but people with rosacea, particularly the spots-and-pustules type, tend to have much higher numbers. The mites and their bacteria activate the skin's immune system, so they are an important amplifier of inflammation rather than the sole cause.
Is rosacea genetic?
Rosacea often runs in families. A large genetic study found variants near immune-response genes, overlapping with the genetic risk for type 1 diabetes and coeliac disease. Genes raise susceptibility, but environmental triggers are needed to set the condition off.
Why does rosacea cause flushing and burning?
Heat-sensing nerve channels called TRP channels are more numerous and more sensitive in rosacea skin. When activated, they release substances such as substance P and CGRP that widen blood vessels and cause flushing, burning and stinging.
Key takeaways
- Rosacea has several interacting causes, not a single one.
- The cathelicidin-KLK5 pathway drives redness, inflammation and new blood vessels.
- Sensitive nerves explain flushing, burning and stinging.
- Demodex mites amplify inflammation, especially in papulopustular rosacea.
This page summarises Chapter 2 of Understanding Rosacea: Your Complete Guide. The full chapter, with references, is in the free PDF.
Download the free Rosacea Guide (108-page PDF) →
Written and medically reviewed by Professor Vishal Madan, MBBS (Hons), MD, FRCP, MBA, Consultant Dermatologist, Laser and Dermatological Surgeon (GMC 6036936).
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This page provides general information about rosacea and is not a substitute for personal medical advice. Please discuss your symptoms and treatment with a qualified healthcare professional.